Defrosting system for refrigeration installation



Dec. 24, 1963 E. J. KOCHER ETAL 3,115,017

DEFROSTING SYSTEM FDR REFRIGERATION INSTALLATION 2 Sheets-Sheet 1' FiledMarch 7, 1962 CONDENSER VER (I RECEI CONDENSER (I RECEIVER I) INVENTORSE. J. KOCHER y J. /V. LONG MM! 8% A-rranmsys 3,115,017 DEFROSTING SYSTEMFOR REFRIGERATION INSTALLATION Erich J. Kocher and Joseph N. Long,Milwaukee, Wis,

assignors to Vilter Manufacturing Corporation, Milwaukee, Wis., acorporation of Wisconsin Filed Mar. 7, 1962, Ser. No. 178,004 3 Claims.(Cl. 62155) The present invention relates generally to improvements inthe art of defrosting refrigeration installations, and it relates morespecifically to an improved system and apparatus for defrosting theevaporators or cooling coils of space cooling installations with the aidof warm The primary object of this invention is to provide a simple buthighly effective system for periodically defrosting refrigerated spacecooling installations.

The defrosting of refrigeration installations has heretofore beeneffected primarily with three well known systems, namely, the waterdefrost system; the electrical system; and the hot gas system. Theprimary objections to these prior systems have been as follows:

The water defrost system requires large quantities of Water, specialwater disposal facilities, costly plumbing, danger of freeze-up due toleaky valves, and danger of water pan overflow due to ice accumulationor the like.

The electrical defrost system is not only somewhat hazardous butrequires expensive electric power wiring, control switches, and heaters.

The hot gas defrosting system generally requires extra refrigerantpiping such as hot gas and liquid return lines,

hot gas valves and liquid relief valves, storage space for condensedliquid or boil oif equipment such as thermo banks or heat cells.

While the idea of utilizing Warm air for defrosting purposes has alsobeen proposed in connection with individual household refrigeratorcabinets, these prior proposals lacked suitable structure sufiicient toeffectively apply the principles in larger commercial space coolersembodying one or more independent or segregated spaces to be cooled.

It is therefore an important object of the present invention to providean improved system and apparatus for utilizing warm air to effectautomatic and eflicient defrosting of one or more cooling areas orspaces in a dependable manner.

Another object of the invention is to provide an improved air coolingsystem and apparatus with an extremely simple and economicalautomatically operable warm air defrosting means which obviates thedisadvantages heretofore attendant and other available defrostingsystems.

Another object of my invention is to provide a novel and improved warmair defrosting system for a refrigeration plant by means of whichdefrosting is accomplished automatically by merely closing therefrigerant valves and adjusting a pair of dampers so that warm air froman adjacent non-refrigerated space is forced over and about the coolingcoil until defrosting has been accomplished.

Still another object of my present invention is to provide a simple andimproved defrosting system which is highly flexible and readilyadaptable for use in defrosting either a single or a multiplicity ofrefrigerated spaces in a most efficient manner.

These and other objects and advantages of the present invention willbecome apparent from the following detailed description reference beingmade to the accompanying drawings in which:

PEG. 1 is a fragmentary vertical section through a single typicalrefrigerated space or cooler embodying the improved defrosting systemwith the refrigerating apparatus tes Patent 2 being diagrammaticallyillustrated and with the dampers being shown in position whereby thedefrosting cycle is inactive;

FIG. 2 is a similar section but showing the dampers moved to a positionwherein the defrosting cycle is effective;

FIG. 3 is a somewhat reduced horizontal section through adjacent coolersof a typical multiple refrigerator system diagrammatically illustratingthe improved defrosting system applied to and utilized in conjunctionwith the several coolers or compartments;

FIG. 4 is a similarly reduced rear elevation of the multiple system ofFIG. 2;

FIG. 5 is a typical wiring diagram providing for automatic operation ofthe multiple system of FIGS. 2 and 3.

While the improvements have been shown and described herein as beingadvantageously embodied in either a single or multiple unit coolingsystem having cooling units of a particular construction and in whichthe defrosting cycles are automatically controllable in a specificmanner, it is not desired or intended to thereby unnecessarily limit orrestrict the use and operation of the invention by reason of suchspecific illustration; and it is furthermore contemplated that thedescriptive terminology used herein shall be given the broadest possibleinterpretation consistent with the disclosure.

Referring now to the drawings and particularly FIGS. 1 and 2 thereof,the refrigerated space or cooler is designated generally by the numeral6, the walls 7 thereof being well insulated from the surrounding area inthe usual manner. Access to the refrigerated space 6 is obtained througha door, not shown, and a compartment 8 within or immediately adjacent tothe space 6 contains an open-ended casing 9 which houses the heatexchanger or cooling coils it) of the refrigerant circulating system.Refrigerant is supplied to and circulated through the cooling coil 10 bya motor driven compressor 11 which has its suction or inlet sidecommunicating with one end of the coil 10 by way of the conduit 12 withits discharge or high pressure side communicating with the other end ofthe coil 10 via the usual condenser 13 and receiver 14 through theconduit 15 and expansion valve 19. In accordance with customarypractice, a fan or blower 16 driven by a motor 16' is also housed in thecasing 9 and is adapted to circulate air from within the space 6 throughthe end opening 17 of the casing 9 as indicated by the arrows in FIG. 1and over the cooling coils 9 where the air is cooled and is thenconducted through the casing opening 18 and back into the space 6. Thesystem and apparatus thus far described is old and well-known withvarious means for periodically defrosting the cooling coils 9 havingheretofore been employed.

In practicing the present invention, the ice accumulations which buildup on the cooling coils 9 during operation of the re rigeratingapparatus are periodically removed by ntilizing the relatively warm airfrom the space 20 outside of the insulated walls 7 which define therefrigerated space 6 for defrosting purposes. A motor driven fan orblower 21 is thus mounted in the warm space or room 20 adjacent theexterior of one of the walls 7 in proximity to the compartment 8, andthe discharge side of the blower 21 is placed in communication with theinterior of the casing 9 by means of a .warm air duct 22. terminating at23 Within the casing 9 upstream of the coils 1t) and between these coilsand the casing end opening 17. To provide for circulation of warm airover the cooling coils and entirely within the casing 9 as willhereinafter more fully appear, a return air duct 24 is provided, one endof the return air duct terminating at 25 downstream of the coils 16' andbetween these coils and a partition 26 provided with an opening 27 andlocated in the casing 9 somewhat in advance of the fan 16.

3 The return air duct leads to the space exteriorly of the refrigeratedspace or room, and a drain passage 28 located below the cooling coils1t) communicates with the duct 24 to conduct defrost water thereto fordisposal in an exteriorly located waste pipe 29 or the like.

During the refrigerating cycle, the ends 23, 25 of the ducts 22, 24respectively are closed and the openings 17, 27 of the casing 9 areopen. For this purpose, a pair of swingably mounted dampers 31, 32respectively are provided, and these dampers are shown in theireffective positions for the refrigerating cycle in FIG. 1 with damper 31closing the end 23 of the warm air duct 22 and damper 32 closing the end25 of the return air duct 24. Obviously, during the refrigerating cycle,the circulating fan 16 is in operation and the warm air blower 21 isoff. When an excess of frost or ice has accumulated on the cooling coils10, the dampers 31, 32 are swung to the positions shown in FIG. 2 toclose the casing openings 17, 27 respectively and open the warm air duct22 and the return air duct 24. For this purpose, a damper act-uatingmotor 33 or the like may be provided, the motor 33 being operativelycoupled to the dampers 31, 32 by suitable actuating mechanism such asthe levers 34, 35, 36 and the links 27, 38 shown. With the cooling coilsection of the casing 9 thus sealed off from the refrigerated space bythe dampers 31, 32 and with the ducts, 22, 24 open to the sealed area,the fan 16 is shut off and the blower 21 is turned on. Warm defrost airis thereby circulated through the duct 22 over and about the coils 19and then exteriorly of the space 6 to exhaust, and the defrost waterfrom the coils 10 is simultaneously conducted with the return air toexhaust via the drain 28 and duct 24. This operation continues until thecoils 10 are sutficiently defrosted whereupon the dampers are returnedto the positions shown in FIG. 1 and the blower 21 is turned off and fan16 placed in operation.

As already indicated, the defrosting system thus shown and described isapplicable either to a single refrigeration unit or to a multiple unitsystem as shown diagrammatically in FIGS. 3 and 4. In such a multipleunit system, each of the refrigerated spaces 6 is provided with one ofthe cooling units above described and comprising the casing 9 and thecirculating fan 16 and cooling coils 10 housed therein. However, only asingle warm air blower 21 need be provided for circulating warm defrostair through a main supply duct 4t) to each of the cooling units viatheir respective branch ducts 22, and the warm air and waste water isremoved from each cooling unit through their respective return ducts 24and drains 28 to a common return air and condensate duct 41. In suchmultiple system, the refrigeration cycle may likewise be effected by asingle centrally located compressor, condenser and receiver.

The control of the refrigerating and defrosting systems may be performedin any desired manner either manually or automatically, and the wiringdiagram shown in FIG. 5 typifies a control for the multiple unit systemshown in FIGS. 3 and 4, such control also being readily applicable to asingle unit system. In FIG. 5, the switches and timers are shown intheir positions for the normal cooling cycle with each of the threeloads being controllable by its respective temperature control tomaintain the individual temperature desired for each unit. In thiscontrol system, a suitable thermostat 43 is located in each of therefrigerated spaces 6, and each thermostat is electrically connected toa suitable timer 44 set for timing the defrosting cycle. In addition,each room thermostat 43 is electrically coupled to a solenoid valve 45controlling flow through the liquid refrigerant line 15 between thereceiver 14 and coils 10, and each thermostat is additionally coupled toa solenoid valve 46 controlling flow through the suction line 12 betweenthe coils 10 and compressor 11. Each timer 44 is electrically connectedto its respective damper motor 33 which in turn throws a switch 47controlling the respective cold air cir- 4 culating fans 16 through itsmotor 16, the switches 47 likewise controlling the operation of the warmair defrost blower 21 through its motor 21'.

Accordingly, when one thermostat 43 is satisfied, it will open thecircuit to its respective liquid and suction solenoid valves 45, 46,respectively, thus stopping the circulation of refrigerant. Periodicallyat preset times, the defrost timer 44 through a double-throw switchtherein will also stop the refrigerant circulation by disconnecting thethermostat 43 and solenoid valves 45, 46 and the position of the dampermotor 33 will be reversed. At the first movement of the damper motor 33,the end switch attached to its shaft breaks the circuit to the fan motor16 to stop the cool air circulating fan 16. As the damper motor 33approaches the opposite end of travel, the end switch on its shaftcloses the circuit to start the defrosting blower motor 21 and therebyoperate the blower 21. During operation of the motor 21, the dampers 31,32 are in the position shown in FIG. 2 so that warm defrost air iscirculated through the ducts 22, 24 and over the cooling coils 10. Atthe end of the defrost period, the timer 44 reverses the position of itssingle-pole, double-throw switch which runs the damper motor 33 back toits original position. At this time, the liquid and suction valves 45,46 are also opened to restore refrigeration, and as soon as the dampermotor 33 starts to move, the end switch on its shaft stops thedefrosting blower 21. As the dampers 31, 32 approach the positions shownin FIG. 1, the fan motor 16 is restarted to operate the cool aircirculating fan 16. It should be understood that one defrosting blowermay be used for all of the air units as above indicated, and the endswitch on the shaft of each of the damper motors 33 will start theblower 21 whenever defrosting is required. It is, of course, preferableto set the defrosting timers so as to defrost the several units atstaggered intervals whenever this control system is used in a multipleunit system.

Various modes of carrying out the invention are contemplated as beingwithin the scope of the following claims particularly pointing out anddistinctly claiming the subject matter which is regarded as theinvention.

We claim:

1. In a refrigerator defrosting system, means providing an enclosedspace to be refrigerated, a housing having open ends and located withinsaid space, a refrigerant air cooling coil confined within said housing,a refrigerant supply means, valve means for normally connecting saidrefrigerant supply means to said coil, a fan for normally circulatingair from said space through said housing in contact with said coil andback to said space, means for periodically interrupting the delivery ofrefrigerant to said coil by said valve means and for simultaneouslyarresting operation of said fan, means for sealing the interior of saidhousing on both sides of said coil from said space during such periodsof interruption and for simultaneously placing the interior of saidhousing in communication with the atmosphere exterior of said enclosedspace, and a blower for circulating warm air from the exterior throughsaid sealed housing portion in contact with said coil and back to theexterior whenever said refrigerant delivery and fan operation isinterrupted.

2. In a refrigerator defrosting system, means providing an enclosedspace to be refrigerated, a housing having open ends and located withinsaid space, a refrigerant air cooling coil confined within said'housing,means forming passageways extending from the atmosphere exterior of saidspace to opposite sides of said coil within said housing, means normallyclosing said passageways to seal the interior of said housing from theexterior atmosphere, a refrigerant supply means, valve means fornormally connecting said refrigerant supply means to said coil, a fanfor normally circulating air from said space through said housing incontact with said coil and back to said space, means for periodicallyinterrupting the delivery of refrigerant to said coil by said valvemeans and for simultaneously arresting operation of said fan, means foractuating said closure means to open said passageways and simultaneouslyseal the interior of said housing on both sides of said coil from saidspace during such periods of interruption, and a blower for circulatingwarm air from the exterior through said sealed housing portion incontact with said coil and back to the exterior whenever saidrefrigerant delivery and fan operation is interrupted.

3. In a refrigerator defrosting system, means providing an enclosedspace to be refrigerated, a housing having open ends and located withinsaid space, a refrigerant air cooling coil confined within a medialportion of said housing between the open ends thereof, means formingpassageways extending from the atmosphere exterior of said space toopposite sides of said coil within said housing, a pair of swingablymounted dampers normally closing said passageways to seal the interiorof said housing from the exterior atmosphere, a refrigerant supplymeans, valve means for normally connecting said refrigerant supply meansto said coil, a fan for normally circulating air from said space throughsaid housing in contact with said coil and back to said space, means forperiodically interrupting the delivery of refrigerant to said coil bysaid valve means and for simultaneously arresting operation of said fan,means for simultaneously swinging said dampers to open said passagewaysand simultaneously seal the interior of said housing on both sides ofsaid coil beyond said passageways from said space during such periods ofinterruption, and a blower for circulating warm atmospheric air from theexterior only through said sealed housing portion and in contact withsaid coil and then back to the exterior whenever said refrigerantdelivery and fan operation is interrupted.

References Cited in the file of this patent UNITED STATES PATENTS2,525,868 Corhanidis Oct. 17, 1950 2,896,425 Dunbar July 28, 19592,939,295 Robson June 7, 1960 3,004,400 Mann et al. Oct. 17, 19613,028,734 Weinstein Apr. 10, 1962

1. IN A REFRIGERATOR DEFROSTING SYSTEM, MEANS PROVIDING AN ENCLOSEDSPACE TO BE REFRIGERATED, A HOUSING HAVING OPEN ENDS AND LOCATED WITHINSAID SPACE, A REFRIGERANT AIR COOLING COIL CONFINED WITHIN SAID HOUSING,A REFRIGERANT SUPPLY MEANS, VALVE MEANS FOR NORMALLY CONNECTING SAIDREFRIGERANT SUPPLY MEANS TO SAID COIL, A FAN FOR NORMALLY CIRCULATINGAIR FROM SAID SPACE THROUGH SAID HOUSING IN CONTACT WITH SAID COIL ANDBACK TO SAID SPACE, MEANS FOR PERIODICALLY INTERRUPTING THE DELIVERY OFREFRIGERANT TO SAID COIL BY SAID VALVE MEANS AND FOR SIMULTANEOUSLYARRESTING OPERATION OF SAID FAN, MEANS FOR SEALING THE INTERIOR OF SAIDHOUSING ON BOTH SIDES OF SAID COIL FROM SAID SPACE DURING SUCH PERIODSOF INTERRUPTION AND FOR SIMULTANEOUSLY PLACING THE INTERIOR OF SAIDHOUSING IN COMMUNICATION WITH THE ATMOSPHERE EXTERIOR OF SAID ENCLOSEDSPACE, AND A BLOWER FOR CIRCULATING WARM AIR FROM THE EXTERIOR THROUGHSAID SEALED HOUSING PORTION IN CONTACT WITH SAID COIL AND BACK TO THEEXTERIOR WHENEVER SAID REFRIGERANT DELIVERY AND FAN OPERATION ISINTERRUPTED.